Cellular molded article in mold pattern having surface skin and producing method thereof

ABSTRACT

A cellular molded article in a mold pattern having the surface skin, which has an excellent releasing property from a metal mold as well as an excellent printing property of a design formed on a surface of metal mold, and a producing method thereof are provided.  
     The cellular molded article in a mold pattern having the surface skin and a producing method thereof, in which, at least a face of surface skin material, which contacts with a metal mold, is an olefin thermoplastic elastomer sheet which is composed of an olefin resin without containing a polyethylene resin as its matrix, and pre-expanded beads, which are employed for an expansion molding in a mold pattern, are pre-expanded beads of an olefin resin.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is a division of Ser. No. 09/950,699, filed Sep.13, 2001, which is based on Japanese Application No. 2001-016528 filedJan. 25, 2001.

TECHNICAL FIELD

[0002] This invention relates to a cellular molded article in a moldpattern having a surface skin, which is used for such as the interiortrim material of an automobile, and a producing method thereof.

BACKGROUND OF THE INVENTION

[0003] As a conventional producing method of a cellular molded articlehaving a surface skin in this kind, it is known as a so-calledsimultaneous unification molding to one piece that, for example, oneither one of two metal molds by which a mold pattern is formed, asurface skin material of thermoplastic resin is arranged, and afterclamping the metal molds, pre-expanded beads are fed into this moldpattern, then the pre-expanded beads are expanded and melt united eachother by steam heating, and at the same time, these pre-expanded beadsand the above mentioned surface skin material of thermoplastic resin aremelt united together to one piece.

[0004] In this simultaneous unification molding to one piece, in eachinside of the above mentioned two metal molds, a chamber connected witha steam valve, a decompression valve and such others are provided. And,on the one metal mold to which the above mentioned surface skin materialwill be arranged, a plural number of decompression holes which connectwith the above mentioned chamber are provided, at the same time, on theother metal mold, a plural number of decompression holes which connectwith the above mentioned chamber are provided. And, at a time of theabove mentioned expansion molding, by means of supplying steam into themold pattern from the steam holes on the above mentioned other metalmold, the filled pre-expanded beads in this mold pattern are heatexpanded.

[0005] In this step, in order to make an effective expansion molding bypre-heating the above mentioned surface skin material, before arrangingthis surface skin material, by means of supplying steam into the abovementioned chamber, the above mentioned other metal mold is oftenpre-heated.

[0006] However, in a case of preheating the above mentioned one metalmold as in the above, if an olefin thermoplastic resin elastomer isemployed as the above mentioned surface skin material, after molding it,at a time of mold releasing of the cellular molded article in the moldpattern having the surface skin from the above mentioned one metal mold,the above mentioned surface skin material will stick on the abovementioned one metal mold, and therefore it will often cause a hardrelease from the above mentioned one metal mold.

[0007] Usually, before releasing it, it is cooled down by water or thelike, but it will not be sufficient. While, a long time cooling is notpreferable due to a longer producing cycle.

[0008] At a time of releasing the cellular molded article in the moldpattern having the surface skin after the end of molding, if the abovementioned surface skin material sticks on the metal mold as in theabove, an automatic releasing of the molded article from the moldingmachine becomes hard, subsequently, it will raise its production cost bya longer time of molding cycle, or by addition of equipment, tools orthe like for releasing the molded article from the molding machine.Furthermore, as releasing the stuck molded article by force from theface of metal mold, there is a problem that design of the surface skinwill be deteriorated.

SUMMARY OF THE INVENTION

[0009] This invention is to solve the above mentioned problems, and evenin a case of preheating the above mentioned one metal mold, sticking thesurface skin material on the above mentioned one metal mold willpractically not be appeared, and therefore, it is an object to provide aproducing method of the cellular molded article in the mold patternhaving the surface skin and a molded article thereby, which are freefrom problems of the molding operation.

DISCLOSURE OF THE INVENTION

[0010] To achieve the above mentioned object, an essential featureresiding in the invention which is claimed is that, a measure forproducing method of the cellular molded article in the mold patternhaving a surface skin is that, a producing method which is, afterthermoforming of a surface skin material along by a metal mold face ofeither one of two metal molds which compose a mold pattern, by means ofexpansion molding in this mold pattern, the above mentioned surface skinmaterial is melt united to one piece with a surface of cellular moldedarticle in the mold pattern to be molded, and at least a face of theabove mentioned surface skin material, which contacts with a metal mold,is an olefin thermoplastic elastomer sheet which is composed of anolefin resin without containing a polyethylene resin as its matrix, andpre-expanded beads, which are employed for an expansion molding in themold pattern, are pre-expanded beads of an olefin resin.

[0011] An essential feature residing the invention which is claimed isthat, a measure that at least a face of the above mentioned surface skinmaterial contacting with a metal mold is composed of a domain, whichcontains a polyethylene resin as its composing raw material resin and isformed by dynamic curing, and an olefin thermoplastic elastomer sheetwhich is composed of an olefin resin without containing a polyethyleneresin as a matrix, and pre-expanded beads to be employed for anexpansion molding in the mold pattern are pre-expanded beads of anolefin resin.

[0012] An essential feature residing in the invention which is claimedis that, a measure is that the above mentioned olefin pre-expanded beadsare pre-expanded beads of a propylene resin.

[0013] An essential feature residing in the invention which is claimedis that, a measure is that the above mentioned olefin pre-expanded beadsare pre-expanded beads of a polyethylene resin.

[0014] An essential feature residing in the invention which is claimedis that, a measure is that the above mentioned olefin resin as a matrixis a polypropylene resin.

[0015] An essential feature residing in the invention which is claimedis that, a measure is that the above mentioned polyethylene resin whichis not included as a matrix is a linear low density polyethylene resin.

[0016] An essential feature residing in the invention which is claimedis that, a measure is that at least the one metal mold is composed of analuminum metal.

[0017] An essential feature residing in the invention which is claimedis that on the surface of the above mentioned one metal mold, a designpattern, which will be printed on a sheet at a time of thermal formingof the sheet, is attached.

[0018] An essential feature residing in the invention which is claimedis that, a measure for the cellular molded article in the mold patternhaving the surface skin which is prepared by that, after thermo-formingof a surface skin material along by either one of metal mold face of twometal molds which compose a mold pattern, by means of expansion moldingin this mold pattern, the above mentioned surface skin material is meltunited to one piece with a surface of cellular molded article to bemolded, and at least one face of the above mentioned surface skinmaterial which contacts with a metal mold is composed of an olefinthermoplastic elastomer sheet which is composed of an olefin resinwithout containing a polyethylene resin as a matrix, and pre-expandedbeads which will be employed for an expansion molding in the moldpattern are pre-expanded beads of an olefin resin.

[0019] An essential feature residing in the invention which is claimedis that, a measure for the cellular molded article in the mold patternhaving the surface skin is that, at least one face of the abovementioned surface skin material which contacts with a metal mold is anolefin thermoplastic elastomer sheet composed of an olefin resin withoutcontaining a polyethylene resin, and pre-expanded beads, which will beemployed for an expansion molding in the mold pattern, are pre-expandedbeads of an olefin resin.

[0020] An essential feature residing in the invention which is claimedis that, a measure for the interior trim material of an automobilecomprises the cellular molded article in the mold pattern having thesurface skin which is claimed.

[0021] An essential feature residing in the invention which is claimedis that, a measure for the cellular molded article in the mold patternhaving the surface skin is that pre-expanded beads of the abovementioned olefin resin are pre-expanded beads of a polypropylene resin.

[0022] An essential feature residing in the invention which is claimedis that, a measure for the cellular molded article in the mold patternhaving the surface skin is that pre-expanded beads of the abovementioned olefin resin are pre-expanded beads of a polyethylene resin.

[0023] An essential feature residing in the invention which is claimedis that, a measure for the cellular molded article in the mold patternhaving the surface skin is that the above mentioned olefin resin as amatrix is a polypropylene resin.

[0024] An essential feature residing in the invention which is claimedis that, a measure for the cellular molded article in the mold patternhaving the surface skin is that the above mentioned polyethylene resinwhich is not included as a matrix is a ar low density polyethyleneresin.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For the better understanding of the invention as well as otherobjects and features thereof, reference is made to the followingdetailed description to be read in conjunction with the accompanyingdrawings, wherein:

[0026]FIG. 1 illustrates a sectional side view of the cellular moldedarticle in the mold pattern having the surface skin of a polyolefinresin.

[0027]FIG. 2 illustrates a sectional side explanation view that, in aproducing method of cellular molded article in the mold pattern havingthe surface skin of polyolefin resin, it is shown a state that a TPOsurface skin material is arranged on the surface of the one metal moldand then clamped.

[0028]FIG. 3 illustrates a sectional side explanation view in which astate of feeding pre-expanded beads of a polyolefin resin into a moldpattern is shown.

[0029]FIG. 4 illustrates a sectional side explanation view in which,after feeding pre-expanded beads of a polyolefin resin, a state offeeding steam into a mold pattern is shown.

[0030]FIG. 5 illustrates a sectional side explanation view in which astate of vacuuming inside of a mold pattern is shown.

[0031]FIG. 6 illustrates a sectional side explanation view in which astate of feeding steam into a mold pattern and expanding pre-expandedbeads of a polyolefin resin are shown.

[0032]FIG. 7 illustrates a sectional side view of the cellular moldedarticle in the mold pattern having the surface skin of a polyolefinresin, which is released from a mold pattern and thus edge part of thesurface skin material is attached as it is molded.

[0033]FIG. 8 illustrates a sectional side view of the cellular moldedarticle in the mold pattern having the surface skin of a polyolefinresin, in which a dual layer surface skin material is employed.

[0034] In the above mentioned drawings, marks represent as follows;

[0035]1 cellular molded article in the mold pattern having the surfaceskin of a polyolefin resin

[0036]2 cellular molded article of a polyolefin resin

[0037]3 TPO surface material

[0038]4 mold pattern

[0039]5 the one metal mold

[0040]6 the other metal mold

[0041]7 inside of the mold pattern

[0042]8 pre-expanded beads of a polyolefin resin

[0043]13 thermoplastic surface skin material for outer layer

BEST MODE FOR PRACTICING THE INVENTION

[0044] Embodiments of this invention are described below based on theattached drawings. As illustrated in FIG. 1, the cellular molded articlein the mold pattern having the surface skin of a polyolefin resin 1comprises the cellular molded article in the mold pattern of apolyolefin resin 2, which is formed to such as U-shape in sectional sideview, and TPO (olefin thermoplastic elastomer) surface skin material 3,which is melt united to one piece with surface 2 a of said cellularmolded article in the mold pattern of a polyolefin resin.

[0045] The above mentioned cellular molded article in the mold patternof polyolefin resin 2 is a molded article by expansion molding in themold pattern of pre-expanded beads of a polyolefin resin pre-expandedbeads. As the above mentioned polyolefin resin, for example, low densitypolyethylene, medium density polyethylene, high density polyethylene, arlow density polyethylene, ethylene-vinyl acetate copolymer, propylenehomopolymer, ethylene-propylene random copolymer,ethylene-propylene-butene random terpolymer, propylene-vinyl chloridecopolymer, propylene-butene copolymer, propylene-maleic anhydridecopolymer, and polyethylene resin or polypropylene resin of poly(butene-1) or the like can be mentioned among others, and these can beused alone or as a mixture of not less than two of them.

[0046] This polyolefin resin is preferably not cross linked however, itmay also be cross-linked by using a peroxide, radiation or the like.

[0047] Furthermore, a mixture of this polyolefin resin and otherthermoplastic resin can be employed. As such kind of thermoplasticresin, in a case of blending with the above mentioned polypropyleneresin, for example, low density polyethylene, ar low densitypolyethylene, aromatic vinyl polymer, polybutene, and ionomer can bementioned among others. While, in case of blending with the abovementioned polyethylene resin, for example, aromatic vinyl polymer,polybutene and ionomer can be mentioned among others. And in thesecases, as an amount of the thermoplastic resin to be blended with ispreferably not more than 20 parts by weight against 100 parts by weightof a polyolefin resin, more preferably 5 to 10 parts by weight.

[0048] The above mentioned pre-expanded beads of polyolefin resin 8 canbe produced for example by a process that a polyolefin resin as in theabove is molded to pellet shape in advance, this polyolefin resin pelletis made to be impregnated with a volatile foaming agent in an autoclaveand then is dispersed in water in keeping stirring, and after heating itup until a prescribed foaming temperature, by means that this dispersedpellet in water is released into a low pressure zone, and thus, it isproduced in a pre-expanded state.

[0049] As an expansion rate when these pre-expanded beads of apolyolefin resin 8 are expanded in the mold pattern, in a case of lessthan 3 times, buffer property or the like of an obtained cellular moldedarticle in the mold pattern of polyolefin resin 2 tends to be reduced,while in a case of more than 60 times, shrinkage of cellular moldedarticle in the mold pattern of a polyolefin resin 2 becomes too largeand also its strength or the like becomes low due to excessive softness,therefore, it is desirable 3 to 60 times, preferably 5 to 50 times, morepreferably 8 to 45 times, and most preferably 10 to 35 times. As suchpre-expanded beads of a polyolefin resin 8, for example, Eperan PP(trade name, made by Kanegafuchi Chemical Industry, Co. expansion rateis 15 times) can be suitably employed among others.

[0050] An olefin copolymer rubber which is employed as the abovementioned TPO surface skin material (olefin thermoplastic elastomer) 3is a non-regular type random elastic copolymer with an olefin as itsmain component, which is, for example, ethylene-propylene copolymerrubber, ethylene-propylene-nonconjugated diene rubber,ethylene-butene-nonconjugated diene rubber, or propylene-butadienecopolymer rubber can be mentioned among others. Among these, anethylene-propylene-nonconjugated diene rubber is particularlypreferable. As a nonconjugated diene, dicyclopentadiene, 1,4-hexadiene,cyclooctadiene, methylene norbornane, ethylidene norbornane can bementioned among others.

[0051] An olefin copolymer rubber is usually cross linked, and asuitable elasticity is caused by this. Therefore, if a cross linking bya peroxide or a radiation works effectively, such method will not belimited whatsoever.

[0052] A preferable olefin resin, which is employed for the abovementioned TPO surface skin material (olefin thermoplastic elastomer) 3,is a polypropylene resin, and as a preferable said polypropylene resin,a polypropylene and/or a random or block copolymer resin of propyleneand α-olefin having two or more carbon atoms. As a typical example ofα-olefin having two or more carbon atoms, ethylene, 1-butene, 1-pentene,3-methyl-1-butene, 1-hexene, 1-decene, 3-methyl-1-pentene,4-methyl-1-pentene or 1-octene can be mentioned among others.

[0053] In the present invention, an olefin resin as in this descriptionis preferably excluding a polyethylene resin, and even if a polyethylenepolymer is included, the minimum amount of it can improve its releasingproperty from a mold pattern. The reason of this property is not clearedyet, but it is thought that, because of a low softening temperature ofpolyethylene resin, this resin sticks on a metal mold, and thus, itsreleasing property gets worse. From the above assumption, for example,in a case of 100% by weight of olefin resin, blending amount of apolyethylene polymer is not more than 15% by weight, preferably not morethan 5% by weight, and more preferably not more than 1% by weight. Themost preferably, it should be reduced further however, as long asachieving an object of the present invention, it is not limited tothese.

[0054] That is, in the present invention, an olefin resin withoutcontaining a polyethylene resin as a matrix is described as in the abovedefinition. TPO surface skin material 3 comprises the above mentionedolefin copolymer rubber (domain) and an olefin resin (matrix), and aratio of each of them can be determined or selected by one's discretionaccording to its object. And as a cross linking agent, which makes apartial cross linking of the above mentioned each mixture, in general,an organic peroxide is suitably employed.

[0055] In a producing method of the above mentioned TPO surface skinmaterial, if necessary, an auxiliary agent such as cross linkingauxiliary agent, flow promoter, inorganic filler, antioxidant,weather-proof agent, anti-static agent, pigment can be blendedtherewith.

[0056] Furthermore, as a coating material for scratch protection, whichcomprises a thermoplastic elastomer and which is coated on the sheetsurface, it is preferably an urethane or acrylic coating material.

[0057] As a processing method of a laminated surface skin material inwhich such material is employed, it can be mentioned among others that,during a processing or after the processing of sheet molding by a methodof calendar molding or T-die extrusion molding of a thermoplasticelastomer according to the above mentioned method or the like, aresinous cellular article layer is laminated, and then, in its lowerstream process, a coating material is coated on a surface ofthermoplastic elastomer which will be the utmost outer layer by acoating machine such as gravure coater.

[0058] Next, a producing method of the cellular molded article in themold pattern having the surface skin of polyolefin resin 1 will beexplained. As illustrated in FIG. 2 to FIG. 7 inclusive, a producingmethod of the cellular molded article in the mold pattern having thesurface skin of olefin resin 1, which is relating to this embodiment ofthe present invention, is that on the one metal mold 5 of two metalmolds 5 and 6, which compose mold pattern 4, TPO surface skin material 3is arranged and clamped them, after then pre-expanded beads of apolyolefin resin 8 are fed into this mold pattern 7, and, by means ofsteam heating, these pre-expanded beads of a polyolefin resin 8 areexpanded to make melt uniting together, and at the same time, thesepre-expanded beads of a polyolefin resin 8 are melt united to one piecewith the above mentioned TPO surface skin material 3.

[0059] That is, as illustrated in FIG. 2, the above mentioned TPOsurface skin material 3 is arranged on the above mentioned one metalmold 5, and then the mold pattern is clamped.

[0060] At this stage, the above mentioned mold pattern 4 is, forexample, composed of two metal molds 5 and 6, which are capable to clampand open in vertical direction.

[0061] In these two metal molds 5 and 6, the above mentioned one metalmold 5 is, for example, composed of a concave shape in sectional sideview, and chamber 5 b is formed in its inside, and a plural number ofdecompression holes 5 c, which are connected with the above mentionedchamber 5 b, are formed on its surface 5 a side. And, the abovementioned chamber 5 b is connected with a steam valve A1, adecompression valve B1 and a drain valve C1 respectively. The othermetal mold 6 a is, for example, composed of a convex shape in sectionalside view, and chamber 6 b is formed in its inside, and a plural numberof steam holes 6 c, which are connected with the above mentioned chamber6 b, are formed on its surface 6 a side. And, the above mentionedchamber 6 b is connected with a steam valve A2, a decompression valve B2and a drain valve C2 respectively, and feeder 10 for feedingpre-expanded beads of polyolefin resin 8 into the above mentioned moldpattern 7 is provided.

[0062] Arranging the above mentioned TPO surface skin material 3 onsurface 5 a of the one metal mold 5 may be made by that the abovementioned TPO surface skin material 3 is formed in advance to a suitableshape to conform to surface 5 a shape of the above mentioned one metalmold 5 by such as vacuum forming, however, as is in this embodiment, ina case of arranging it by heat forming such as vacuum forming, there isa merit that the labor for forming it in advance can be omitted. And, asa thermo-forming of this TPO surface skin material 3, it is not limitedto vacuum forming but other forming such as compression molding can beapplied.

[0063] At this stage, as a method for vacuum forming, the abovementioned TPO surface skin material 3 is heat-softened beforehand, andit is contacted with the one metal mold 5 as it is, thereafterdecompression valve B1, which is connected with the above mentionedchamber 5 b, is opened or like that.

[0064] In this case, by means that the above mentioned one metal mold 5is heated up to a prescribed temperature by steam or a heater which isseparately mounted on or the like, temperature drop of heat-softened TPOsurface skin material 3 to be contacted with said the one metal mold 5can be minimized, thus there is a merit that a design pattern of the onemetal mold 5 can be effectively printed on TPO surface skin material 3.Further, during the heat molding or in the subsequent expansion moldingin the mold pattern, in order to prevent a heat drop of TPO surface skinmaterial 3, heating up by such as a heater may continue during thethermo-forming or even in after it, or a stepwise heating which ischanging the setting temperature in stepwise from the beginning may alsobe done.

[0065] And, in a case that the above mentioned TPO surface skin material3 comprises a polyolefin resin, when the temperature of the one metalmold 5 before the thermo-forming operation is at in a range of 60 to150° C., preferably at 60 to 130° C., more preferably at 70 to 120° C.,as the above mentioned TPO surface skin material 3 can be thermo-formedin a suitable softening condition, there is a merit to make a goodfinishing.

[0066] While, in a case that the cellular molded article in the moldpattern having the surface skin of a polyolefin resin 1 to be obtainedby this process is, for example, required to have a fitting tool or thelike, on surface 6 a of the above mentioned other metal mold 6, aprescribed shaped inserting member (not shown) is arranged in advance,and at a time of expanding operation in the mold pattern of the abovementioned pre-expanded beads of a polyolefin resin 8, this insertingmember may be melt united to one piece with the cellular molded articlein the mold pattern of a polyolefin resin 2.

[0067] Next, as illustrated in FIG. 3, pre-expanded beads of apolyolefin resin 8 are fed into mold pattern 7 from the above mentionedfeeder 10.

[0068] At this stage, as TPO surface skin material 3 is arranged onsurface 5 a of the above mentioned one metal mold 5 in a condition ofclamped, the inside air can be evacuated by only steam holes 6 c of theabove mentioned other metal mold 6, consequently, to make a smoothfeeding of the above mentioned pre-expanded beads of a polyolefin resin8, a small opening between the two metal molds may be made so that thesepre-expanded beads of a polyolefin resin 8 will not go through, but theinside air can be evacuated from this small opening at a time of thefeeding.

[0069] And, the above mentioned pre-expanded beads of a polyolefin resin8 may be fed into the above mentioned mold pattern 7 in a state that acompressed gas is penetrated into their insides in advance and an innerpressure in each of them is given, or may be fed in a compressed stateby a compressed gas, or may be fed as they are without giving an insidepressure or compressing.

[0070] Thereafter, as illustrated in FIG. 4, a steam valve A2, whichconnects with chamber 6 b of the above mentioned other metal mold 6, isopened, and steam S is fed into mold pattern 7 through the abovementioned steam holes 6 c, and the above mentioned pre-expanded beads ofa polyolefin resin 8 are heat expanded.

[0071] At this stage, by means that the above mentioned pre-expandedbeads of a polyolefin resin 8 are pre-heated in advance at a lowertemperature than the temperature of their melt uniting together, beforethe regular heating of these pre-expanded beads of a polyolefin resin 8at a higher temperature than the temperature of their melt unitingtogether, pre-expanded beads of a polyolefin resin 8 can be made to asufficiently heated up to a state without causing a problem of meltuniting each other.

[0072] Furthermore, after a pre-heating as in the above, by steaming theabove mentioned pre-expanded beads of a polyolefin resin 8 with steam S,as can be effectively utilizing the latent heat of fed steam S inbetween the above mentioned pre-expanded beads of a polyolefin resin 8,particularly, in a case of forming a thick cellular molded article inthe mold pattern of a polyolefin resin 2 or the like, there is a meritthat the above mentioned pre-expanded beads of a polyolefin resin 8 canbe more uniformly heated.

[0073] And, after the pre-heating, steaming can be made by continuoussteam S supply, or by suspending steam S supply, or, if necessary, in acondition of opening drain valve C2.

[0074] After steaming of the above mentioned pre-expanded beads of apolyolefin resin 8 by steam S, there remains drain (moisture) in betweenthe above mentioned pre-expanded beads of a polyolefin resin 8, and if aregular heating is made as they are, there will happen insufficient meltuniting of pre-expanded beads of a polyolefin resin 8 each other.Therefore, evacuation of the above mentioned drain is desirable.

[0075] As a method for evacuation of this drain, for example, asillustrated in FIG. 5, a method that, decompression valve B2, which isconnected with chamber 6 b of the above mentioned other metal mold 6, isopened and vacuuming inside of mold pattern 7 through the abovementioned steam holes 6 c, or a method that, making a slit between twometal molds 5 and 6 by making a small opening in the mold pattern 4,then a high temperature and dry air, which is however not so high asmelt uniting temperature of pre-expanded beads of polyolefin resin 8, ispenetrated therein so as to evacuate the drain through the abovementioned slit, can be mentioned among others.

[0076] Subsequently, the regular heating is carried out at a highertemperature than the temperature of melt uniting each other of the abovementioned pre-expanded beads of a polyolefin resin 8. This regularheating is carried out, as illustrated in FIG. 6, by supplying steam Sinto mold pattern 7 from the above mentioned steam holes 6 by openingthe above mentioned steam valve A2. At this step, as described in theabove, in a case that, after the steaming by steam S, vacuuming of theabove mentioned mold pattern 7 is carried out for evacuation of thedrain, the above mentioned steam S for the regular heating can besupplied more smoothly into mold pattern 7.

[0077] In addition, the temperature of steam S at this stage ispreferably higher than the temperature at which the above mentionedpre-expanded beads of a polyolefin resin 8 are melt uniting each other.However, in a case of excessively high temperature, shrinkage ofobtained cellular molded article in the mold pattern of a polyolefinresin 2 will become excessively large.

[0078] After the regular heating as described in the above, in order totransfer the heat by steam S into the above mentioned pre-expanded beadsof a polyolefin resin 8 sufficiently, it is desirable to keep in itscondition.

[0079] Subsequently, by opening the above mentioned mold pattern 4, asis illustrated in FIG. 7, cellular molded article in the mold patternhaving the surface skin of a polyolefin resin 1 a which is having edgepart 3 c can be obtained.

[0080] And, before opening the mold pattern, the above mentioned moldpattern 4 may be cooled down in advance. Also, cellular molded articlein the mold pattern having the surface skin of a polyolefin resin 1 awhich has been obtained is preferably dried by such as keeping it in adried room, right after released it from mold pattern 4. While, as isdescribed in this embodiment, in a case that the above mentioned edgepart 3 c is formed by an excessive edge part of the above mentioned TPOsurface skin material 3, after releasing it from the mold pattern, as isdescribed in the above, after drying it or before keeping it in a dryingroom, by cutting off the above mentioned edge part 3 c, cellular moldedarticle in the mold pattern having the surface skin of a polyolefinresin 1, which is illustrated in FIG. 1, can be obtained.

[0081] As is described in the above, the above mentioned pre-expandedbeads of a polyolefin resin 8 is pre-heated and steamed by steam S, andthen, by making a regular heating, when cellular molded article in themold pattern of a polyolefin resin 2 is produced from pre-expanded beadsof a polyolefin resin 8, simultaneously said cellular molded article inthe mold pattern of polyolefin resin 2 can be tightly melt united to onepiece with the above mentioned TPO surface skin material 3, and infurther, cellular molded article in the mold pattern having the surfaceskin of a polyolefin resin 1, in which the above mentioned cellularmolded article in the mold pattern of a polyolefin resin 2 is free frominsufficient melt uniting of pre-expanded beads of a polyolefin resin 8,can be produced.

[0082] Cellular molded article in the mold pattern having the surfaceskin of a polyolefin resin 11 illustrated in FIG. 8 is an example that,on surface 3 a of the above mentioned TPO surface skin material 3,thermoplastic surface skin material for outer layer 13 of one layer islaminated.

[0083] When such laminated TPO surface skin material 3 with at least onelayer of thermoplastic surface skin material for outer layer 13 is meltuniting to one piece with the above mentioned cellular molded article inthe mold pattern of a polyolefin resin 2, as TPO surface skin material 3is hidden by the above mentioned thermoplastic surface skin material forouter layer 13, by means of employing thermoplastic surface skinmaterial for outer layer 13 which comprises a material which will notstick with the one metal mold 5, or in further, has a better printingproperty for the design so that a better appearance can be made,accordingly, there will not need to consider about a sticking problem ofTPO surface skin material 3 with the one metal mold 5 nor about itsappearance problem, and therefore, there is a merit that this TPOsurface skin material 3 can be made from a desirable composition inconsideration of a better melt uniting property with pre-expanded beadsof a polyolefin resin, a better vacuum forming property or like that.

[0084] Furthermore, in the above embodiment 1 and 2 which areillustrated in FIG. 7 and FIG. 8, it was described of a case that theabove mentioned one metal mold 5 is a concave mold (female mold) ofwhich sectional side view is concave shape, however, it is not limitedto this, but it can also be made that the above mentioned one metal moldis a convex mold (male mold) and the other metal mold 6 is a concavemold (female mold).

[0085] As an use of the cellular molded article in the mold patternhaving the surface skin by the present invention, various industrialproducts such as sports goods field or parts for building and housingcan be mentioned. As the interior trim material for an automobile, aninstrument panel, console box, arm rest, head rest, door trim, rearpanel, pillar trim, sun visor, trunk room trim, trunk lid trim, head r,globe box and ceiling material can be mentioned among others.

EXAMPLE

[0086] Next, more details of the present invention will be described byexamples of the invention however, it is not limited to these examples.

Example 1 to 3

[0087] In a female mold and a male mold which compose a mold pattern,after arranging a surface skin material on the above mentioned femalemold by vacuum forming, an expansion molding in this mold pattern wascarried out. In inside of a portion on which a cavity face of the abovementioned female mold is composed, a flow for passing a thermo-medium isformed in meandering shape, and by means of passing steam through thisflow, the temperature of cavity face is kept as shown in Table 1. And,on the above mentioned male mold, steam holes for feeding steam into themold pattern at a time of expansion molding and a feeder for supplyingpre-expanded beads were mounted.

[0088] In this stage, a thermoplastic resin sheet of polyolefine resin(TPO sheet) as the above mentioned surface skin material was employed,and after heating this sheet, it was arranged on the above mentionedfemale mold, then it was shaped by a vacuum pump. As pre-expanded beads,Eperan PP (trade name, produced by Kanegafuchi Chemical Industry Co.,expansion rate was 15 times, its inner pressure was 2 kg/cm²·G given byair pressure in a pressure container in advance) was employed, and afterclamping the mold pattern, these pre-expanded beads were fed into themold pattern through the above mentioned feeder.

[0089] After the feeding of pre-expanded beads, steam (vapor pressurewas 1.5 kg/cm²·G) was fed into the mold pattern through the steam holesmounted on the above mentioned male mold, and pre-heated. Then, aftersteaming of the pre-expanded beads, the drain and steam were suctionedand evacuated by employing a vacuum pump. Thereafter, steam (vaporpressure was 3.2 to 3.7 kg/cm²·G) was fed into the mold pattern againthrough the above mentioned steam holes and a regular heating wascarried out, and then, after cooled down by water, by opening the moldpattern, the cellular molded article in the mold pattern having thesurface skin was obtained. While, cooling of the female mold during theabove mentioned water cooling time was carried out by feeding a cooledwater into the above mentioned flow line.

Comparative Example 1 to 2

[0090] The cellular molded article in the mold pattern having thesurface skin was obtained by the same manner as in example 1 to 3 exceptemploying the surface skin material shown in Table 1.

Comparative Example 3 to 6

[0091] The surface temperature of female mold pattern was changed asshown in Table 1, and comparative example 4 shows the result in whichPef PPAM (trade name of Toray company) was employed as the surface skinmaterial.

[0092] In addition, at a time of opening the mold pattern in example 1to 3 and comparative example 1 to 6, a presence of sticking of thesurface skin material with the female mold pattern was observed. Also, asurface appearance of each of the obtained cellular molded article inthe mold pattern having the surface skin was examined. Its result isshown in Table 1.

[0093] [Evaluation Standard]

[0094] Presence of sticking of the surface skin material with the femalemold pattern

[0095] ⊚: none of presence of sticking with the metal mold

[0096] ◯: some presence of sticking with the metal mold, but it can bereleased without trouble

[0097] ▴presence of sticking with the metal mold is observed andautomatic releasing from the metal mold is difficult

[0098] x: strong sticking with the metal mold and cannot be releasedfrom the metal mold

[0099] Printing property of the design to the molded article;

[0100] ⊚: design of the metal mold is sufficiently printed on

[0101] ◯: design of the metal mold is almost printed on

[0102] ▴: design of the metal mold is printed on, but defect is observed

[0103] x: design of the metal mold is not sufficiently printed on

[0104] Melt uniting property of the beads with the surface skin material

[0105] ⊚: beads are tightly melt united with the surface skin material

[0106] ◯: beads are melt united with the surface skin material

[0107] ▴: beads are melt united with the surface skin material but nottightly

[0108] x: beads are not sufficiently united with the surface skinmaterial TABLE 1 Composition Sticking of surface Surface temperature offemale mold of surface skin Printing Melt uniting property skin material(° C.) material to female property of of beads with surface DomainMatrix Vacuum forming Expansion molding mold pattern design skin Example1 TPO-a R-PP (a) 95 100 ⊚ ⊚ ⊚ EPDM B-PP Example 2 TPO-b R-PP (a) 90 90 ∘∘ ˜ ⊚ ⊚ EPDM R-PP Example 3 TPO-c R-PP (a) 95 95 ⊚ ⊚ ⊚ EPDM LLDPEComparative example 1 TPO-a LLDPE 100 95 x ▴ ˜ ∘ ⊚ EPDM B-PP Comparativeexample 2 TPO-a R-PP (a) 95 95 ▴ ▴ ˜ ∘ ⊚ EPDM LLDPE R-PP Comparativeexample 3 TPO-a R-PP 50 50 ⊚ ▴ ˜ x x EPDM LLDPE B-PP Comparative exampleTPO-a R-PP 50 50 ⊚ ▴ ˜ x ⊚ 4 (*1) EPDM LLDPE B-PP Comparative example 5TPO-a R-PP 50 95 x ▴ ˜ x ⊚ EPDM LLDPE B-PP Comparative example 6 TPO-aR-PP 95 50 ▴ ˜ x ▴ ˜ ∘ x EPDM LLDPE B-PP

[0109] In the above Table 1, it is shown that:

[0110] TPO-a: WT312B, trade name, made by Sumitomo Chemical Industry

[0111] TPO-b: 4652, trade name, made by Sumitomo Chemical Industry

[0112] TPO-c: 8030N, trade name, made by Mitsui Petroleum Chemical Co

[0113] R—PP(a): S-131, trade name, made by Sumitomo Chemical Industry

[0114] LLDPE: FW201-O, trade name, made by Sumitomo Chemical Industry

[0115] *1: Pef PPAM 15025, trade name, made by Toray Co.

EFFECTIVENESS OF THE INVENTION

[0116] A producing method for the cellular molded article in the moldpattern having the surface skin and a molded article thereby which arerelating to the present invention exhibit an excellent effect inprinting of a design of metal mold onto a surface skin material, and anexcellent automatic releasing property from a mold metal. Accordingly,there are a lot of advantageous effects such as a good appearance, easyrecycling or light weight.

[0117] Although the invention has been described in its preferred formwith certain degree of particularity, it is understood that the presentdisclosure of the preferred form has been changed in the details ofconstruction and the combination and arrangement of parts may beresorted to without departing from the spirit and the scope of theinvention as hereinafter claimed.

What is claimed is: 1: A cellular molded article in the mold patternhaving the surface skin, which is characterized in that, the cellularmolded article in the mold pattern having the surface skin which isprepared by that, after thermoforming of a surface skin material alongby either one of metal mold face of two metal molds which compose a moldpattern, by means of expansion molding in this mold pattern, the abovementioned surface skin material is melt united to one piece with asurface of cellular molded article to be molded, and at least one faceof the above mentioned surface skin material which contacts with a metalmold is composed of an olefin thermoplastic elastomer sheet which iscomposed of an olefin resin without containing a polyethylene resin as amatrix, and pre-expanded beads which will be employed for an expansionmolding in the mold pattern are pre-expanded beads of an olefin resin.2: A cellular molded article in the mold pattern having the surface skinas claimed in claim 1, wherein it is characterized in that, the cellularmolded article in the mold pattern having the surface skin is that, atleast one face of the above mentioned surface skin material whichcontacts with a metal mold is an olefin thermoplastic elastomer sheetcomposed of an olefin line resin without containing a polyethyleneresin, and pre-expanded beads, which will be employed for an expansionmolding, are pre-expanded beads of an olefin resin. 3: The interior trimmaterial of an automobile comprises a cellular molded article in themold pattern having the surface skin as claimed in claim
 1. 4: Acellular molded article in the mold pattern having the surface skin asclaimed in claim 1, wherein it is characterized in that, pre-expandedbeads of the above mentioned olefin resin are pre-expanded beads of apolypropylene resin. 5: A cellular molded article in the mold patternhaving the surface skin as claimed in claim 1, wherein it ischaracterized in that, pre-expanded beads of the above mentioned olefinresin are pre-expanded beads of a polyethylene resin. 6: A cellularmolded article in the mold pattern having the surface skin as claimed inclaim 1, wherein it is characterized in that, the above mentioned olefinresin as a matrix is a polypropylene resin. 7: A cellular molded articlein the mold pattern having the surface skin as claimed in claim 1,wherein it is characterized in that, the above mentioned polyethyleneresin which is not included as a matrix is a linear low densitypolyethylene resin.